1. Field of the Invention
This invention generally relates to pressure limiting valves. More specifically, the invention relates to pressure limiting valves having an elongate, tube-like valve housing with an axial inlet opening and at least one outlet opening axially separated from the inlet opening, and whereby an internal valve seat for a ball-shaped valve body is connected to the inlet opening and whereby a valve piston is positioned between the valve body and a closing spring that produces a closing force.
2. Related Technology
Pressure limiting valves of the general type to which the present invention relates are used in fuel return lines by so-called common-rail-systems of combustion engines. Such a common-rail-system features a pressure line, the so-called rail for several injectors. Fuel under high pressure is supplied via the pressure line and can be injected in a dosed manner via the injectors into the combustion engine. The non-injected fuel is sent via the return line into the vacuum line of the fuel pump or into the tank. In the process it is generally necessary to maintain a certain minimum pressure in the low pressure range of the injectors. To that end a pressure limiting valve of the above general type is emplaced in the return, frequently also called a pressure maintenance valve which has the described objective of holding the pressure of the fuel in the low pressure range of the injectors at a defined value or limiting it to this defined value.
It has been seen in practice that under certain operating conditions damage or even total failure to the pressure maintenance valve can occur.
In view of the above, improving the operational security of a pressure limiting valve of the type described and, as a result, avoiding damage or even total failure is desirable.